Use Crete as setting for mystery (6)

I believe the answer is:

secret

I'm a little stuck... Click here to teach me more about this clue!

'for mystery' is the definition.
(I've seen this before)

'use crete as' is the wordplay.
'SECRET' is hidden in amongst the letters.
However, I'm uncertain how this is indicated.

'setting' acts as a link.

Can you help me to learn more?

(Other definitions for secret that I've seen before include "avoiding exposure" , "Cloak and dagger" , "Kept under wraps" , "away from scrutiny" , "Hidden, private" .)

I've seen this clue in The Sun and The Times.

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